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SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
This says, "create a container view showing the user, service 1, and anything directly connected to service 1". It's compatible with a number of diagramming formats too via the Structurizr CLI export command. Here's a PlantUML version of the above diagram, created from the same Structurizr DSL code.
For example, an interactive force-directed graph is better suited to showing and exploring larger quantities of data. Something like D3.js admittedly has a steep learning curve, but makes this relatively straightforward.